Chore(Insight Analytics): feature flag config

Update feature flag configuration to claim it for
group::analytics and point to MR introducing it:
https://gitlab.com/gitlab-org/gitlab/-/merge_requests/35535

ee/config/feature_flags/development/embed_analytics_report.yml

 ---
 name: embed_analytics_report
-introduced_by_url: 
+introduced_by_url: https://gitlab.com/gitlab-org/gitlab/-/merge_requests/35535
 rollout_issue_url:
-group: 
+group: group::analytics
 type: development
 default_enabled: false